Heat Output and Temperature Door Activation, Checking, Comfort
Heat Output and Temperature Door Activation, Checking, Comfort
Test requirements are met, refer to => [ Heating Output and Temperature Door Activation, Testing Requirements ] Heating Output and Temperature Door Activation, Testing Requirements.
- Close the engine hood.
- Close the doors, the windows, the sunroof and the rear lid.
- Open all instrument panel vents.
- Turn on the ignition and activate the ready mode, the engine start by itself if needed (high voltage vehicles).
- Start the engine (not high voltage vehicles).
Set the Climatronic control module (J255) as follows:
• "Auto" for the driver and passenger side (the indicator lamp in the AUTO buttons come on).
• Temperature preset for the driver and front passenger side set to "cold" ("LO" in the Climatronic control module or in the MMI display).
• The A/C compressor is on (the indicator lamp on the AC button comes on).
• Preselect for the fresh air blower "maximum speed" (in the Climatronic control module and in the Multi Media Interface display, level "10" or greater).
• Set the air vent direction using the dial on the display and control head for the driver and passenger side to "footwell" and "instrument panel vents" (in the Climatronic control module and in the MMI)
• The indicator lamp in the AUTO -buttons turns off when performing manual changes for the airflow direction and/or the fresh air blower speed.
• The maximum possible fresh air blower speed depends on several conditions (coolant temperature, vehicle voltage, etc.)
• If the dial for setting the driver side temperature is held for a longer time, then this setting will be taken over as well for the passenger side.
- Set the rear temperature selection potentiometer (G538) to "cold" (installed in the vent in the rear center console).
- Open the vents in the rear center console.
- Perform Guided Fault Finding on A/C system and select the "Read measuring value block" function using the Vehicle diagnostic tester in "Guided Fault Finding".
- Let the A/C run a few minutes with maximum cooling output (A/C compressor is switched on, indicator lamp in the AC button comes on).
- Compare the measured values taken from the evaporator vent temperature sensor (G263) with the measured values taken from the left front upper body outlet temperature sensor (G385) , the right front upper body outlet temperature sensor (G386) , the left footwell vent temperature sensor (G261) and the right footwell vent temperature sensor (G262) ).
Target values
• After 5 minutes, the temperature sensor measured values from the heater core (left front upper body outlet temperature sensor , right front upper body outlet temperature sensor , left footwell vent temperature sensor and right footwell vent temperature sensor) may not be greater than 5 °C (41 °F), than the value of the evaporator vent temperature sensor.
If the required values are not reached, perform a fault finding at a temperature increase on the evaporator
- Using a commercially available thermometer, measure the air coming out of the vents in the rear center console and the rear footwell vents (left and right under the front seats) and compare the measured values with the temperatures displayed in the measured values block.
Target values
• The measured values may be 5 °C (41 °F) greater than the displayed measured values for the temperature sensor.
If the required values are not reached, perform a fault finding at a temperature increase on the evaporator
- Using the dial on the Climatronic control module, set the temperature for the passenger side to "Warm" (display "HI" in the Climatronic Control Module and in the MMI display ).
- Read the measured values displayed in the measured values block (evaporator vent temperature sensor (G263) , left front upper body outlet temperature sensor (G385) , right front upper body outlet temperature sensor (G386) , left footwell vent temperature sensor (G261) and right footwell vent temperature sensor (G262) ).
- Using a commercially available thermometer, measure the temperature of the air coming out of the vents in the rear center console (left and right).
Target values
• The temperature on the right front upper body outlet temperature sensor and right footwell vent temperature sensor increase to above 52 °C (125 °F) an (depending on the engine temperature at the time).
• The temperature on the left front upper body outlet temperature sensor and left footwell vent temperature sensor increases by less than 10 °C (50 °F) in contrast to the measured value of the evaporator vent temperature sensor.
• The measured temperature of the air coming out of the vents in the rear center console increases by less than 20 °C (68 °F).
• Depending on the engine, for example, on the 8 cylinder engine, it may be necessary to increase the engine from 1,200 to 1,500 to reach the required temperature. The heating performance of the engine or coolant flowing through the heater core may not be sufficient when the engine is running in idle to bring the necessary warming energy into the heater core (for example, on an 8 cylinder engine with an idle RPM of approximately 650).
• The actuation of the temperature doors for the rear vents (by the Rear Temperature door Motor (V137) ) is performed by a characteristic curve in the Climatronic control module. If the setting between the left and right side in the Climatronic control module and / or the setting on the Rear Temperature Selection Potentiometer (G538) differs very much, then the temperature doors for the rear vents are no longer set in the end stops. The actuation of the temperature flaps for the temperature of the air coming out of the rear vents depends on the setting of the on the rear temperature selection potentiometer (G538) which has a tendency to be somewhat warmer or cooler the air for the front vents.
• On high voltage vehicles, lower the fresh air blower (V2) speed. The coolant pump (V50) delivery is not always enough to supply the required heat output when the engine is running and the fresh air blower is set to the highest setting.
If the specified values are not reached, check the following
• Repeat the heating output at an engine RPM of approximately 1,500 to 2,000 (at a low fresh air blower speed on high voltage vehicles). If the heating performance is not reached at the engine RPM (fresh air blower speed), the fault is not with the A/C unit but rather inside the coolant circuit (a combination of the A/C system in the coolant circuit, engine coolant pump delivery, the coolant flowing through the heater core, etc. Refer to => [ Heater Core/Housings ] Heater Core/Housings ).
• The actuation and function of the right temperature door motor (V159) , of the left temperature door motor (V158) and the actuation of the front left and right temperature doors; refer to => [ Heater Core Housing Temperature Doors ] Heater Core Housing Temperature Doors, => [ Right Temperature Door Motor (V159) ] Right Temperature Door Motor (V159) and the Vehicle diagnostic tester in "Guided Fault Finding".
• Actuation and function of the rear temperature door motor (V137) and the actuation of the rear left and right temperature door (via the connecting rod), refer to => [ Heater Core Housing Temperature Doors ] Heater Core Housing Temperature Doors and => [ Temperature Regulator Door Motor (V68) and Rear Temperature Door Motor (V137) ] Temperature Regulator Door Motor (V68) and Rear Temperature Door Motor (V137) and the Vehicle diagnostic tester in "Guided Fault Finding".
• Foam seal on heater core for heater of A/C unit, refer to => [ Heater Core Removing and Installing ] Heater Core Removing and Installing.
• The foam seal on the Auxiliary Air Heater Heating Element (Z35) / on the honey comb.
• The separations in the air distribution housing between the left and right side and between rear and front, refer to => [ Air Distributor Housing Doors and Partitions ] Air Distributor Housing Doors and Partitions.
• Coolant regulator (engine coolant may not warm properly if regulator is malfunctioning).
• Check the engine coolant pump for correct function (if the coolant pump is defective, it is possible that not enough coolant is flowing through the heater core for heating in the A/C unit).
• Coolant pump (V50) activation and function (if the coolant pump is faulty, then not enough coolant is flowing through the heater core in the air conditioner for heating). Refer to the Vehicle diagnostic tester in "Guided Fault Finding".
• The coolant pump (V50) maintains the coolant flow through the heater core in the A/C system when the engine is not running for vehicles with a start-stop system and for high voltage vehicles.
- Using the dial on the Climatronic control module, set the temperature on the driver side to "Warm" (display "HI" for the driver and passenger side in the Climatronic control module and in the MMI display).
- Read the measured values of the heater core temperature sensor (left front upper body outlet temperature sensor (G385) , right front upper body outlet temperature sensor (G386) , left footwell vent temperature sensor (G261) and right footwell vent temperature sensor (G262) ).
- Using a commercially available thermometer, measure the temperature of the air coming out of the vents in the rear center console (left and right).
Target values
• The temperature on the right front upper body outlet temperature sensor and right footwell vent temperature sensor increases to above 52 °C (125 °F) within 5 minutes (depending on the engine temperature at the time).
• The temperatures from the temperature sensor displayed in the measure values block (left front upper body outlet temperature sensor , right front upper body outlet temperature sensor , left footwell vent temperature sensor and right footwell vent temperature sensor ) even out within 5 minutes (the difference in temperature is less than 5 °C (41 °F) and the temperature is greater than 52 °C) (125 °F).
• The measured temperature coming out of the vents in the left and right side of the rear center console increases but does not reach the displayed temperatures for the temperature sensor (left front upper body outlet temperature sensor , right front upper body outlet temperature sensor, left footwell vent temperature sensor and right footwell vent temperature sensor ) (has a tendency to be cooler than the setting on the rear temperature selection potentiometer (G538) ).
• Depending on the engine, for example, on the 8 cylinder engine, it may be necessary to increase the engine from 1,200 to 1,500 to reach the required temperature. The heating performance of the engine or coolant flowing through the heater core may not be sufficient when the engine is running in idle to bring the necessary warming energy into the heater core (for example, on an 8 cylinder engine with an idle RPM of approximately 650).
• At the setting "Warm" for the driver and passenger side the specified outflow temperature on the evaporator is controlled to approximately 10 °C (50 °F) by the Climatronic control module.
• On high voltage vehicles, lower the fresh air blower (V2) speed. The coolant pump (V50) delivery is not always enough to supply the required heat output when the engine is running and the fresh air blower is set to the highest setting.
If the specified values are not reached, check the following.
If the specified values are not reached, proceed as follows:
- Set the rear temperature selection potentiometer (G538) to "warm" (installed in the vent in the rear center console).
- Using a thermometer, measure the temperature of the air coming out of the vents in the rear center console and the rear footwells (left and right sides) and compare with the displayed measured values for the temperature sensor (left front upper body vent temperature sensor (G385) , right front upper body vent temperature sensor (G386) , left footwell vent temperature sensor (G261) and right footwell vent temperature sensor (G262) ).
Target values
• The measured air temperature coming out of the vents in the rear center console and the rear footwell vents (left and right side increases and reaches within 5 minutes a value, which is 10 °C (50 °F) less than the small value measured and displayed by the temperature sensors.
• The difference between the measured temperature on the left and right side is less than 5 °C (41 °F).
If the specified values are not reached, check the following:
• Check the actuation and function of the rear temperature door motor (V137) and the actuation of the rear left and right temperature doors (via the connecting rod), refer to => [ Heater Core Housing Temperature Doors ] Heater Core Housing Temperature Doors and => [ Temperature Regulator Door Motor (V68) and Rear Temperature Door Motor (V137) ] Temperature Regulator Door Motor (V68) and Rear Temperature Door Motor (V137) and the Vehicle diagnostic tester in "Guided Fault Finding".
If the specified values are not reached, proceed as follows:
- Using the dial on the Climatronic control module, set the temperature the front passenger side to "Cold" (display "LO" in the Climatronic control module and in the MMI display).
- Compare the displayed measured value from the evaporator vent temperature sensor (G263) to the measured values from the right front upper body outlet temperature sensor (G386) and from the right footwell vent temperature sensor (G262) and then read the measured valued for the left front upper body outlet temperature sensor (G385) and the left footwell vent temperature sensor (G261).
Target values
• The measured and displayed temperatures on the left front upper body outlet temperature sensor on the left footwell vent temperature sensor will change slightly and will remain greater than 52 °C (125 °F) depending on the engine temperature at the time).
• The temperature on the right front upper body outlet temperature sensor and on the right footwell vent temperature sensor will drop and after 5 minutes at the latest, it will reach a value of maximum 10 °C (50 °F) than the values from the evaporator vent temperature sensor.
• Depending on the engine, for example, on the 8 cylinder engine, it may be necessary to increase the engine from 1,200 to 1,500 to reach the required temperature. The heating performance of the engine or coolant flowing through the heater core may not be sufficient when the engine is running in idle to bring the necessary warming energy into the heater core (for example, on an 8 cylinder engine with an idle RPM of approximately 650).
• At the setting "Warm" for the driver and passenger side the specified outflow temperature on the evaporator is controlled to approximately 10 °C (50 °F) by the Climatronic control module. If the temperature setting "cold" is selected for one side, the Climatronic control module will lower the die specified outflow temperature on the evaporator and will control this to approximately 2 °C (35 °F).
• On high voltage vehicles, lower the fresh air blower (V2) speed. The coolant pump (V50) delivery is not always enough to supply the required heat output when the engine is running and the fresh air blower is set to the highest setting.
If the specified values are not reached, check the following.
If the specified values are reached, the test is complete.
Temperature Increase Downstream from Evaporator, Determining Malfunction
